Oils are used for a variety of applications, including providing lubrication for engines and motors to extend lifetime and prevent failure. Oils that are used as lubricants provide lubrication between two moving surfaces, such as for example, bearings and other metal surfaces, to improve motor efficiency and improve motor run life. Additionally, lubricants are useful for carrying away heat that is generated within the motor, thereby reducing the operating temperature. Finally, oil may function as an electrical resistor between the stator and rotor in a motor.
Oils are generally selected based upon a desired viscosity at a specified operating temperature. Preferably, oils are selected to ensure efficient operation of a motor or engine at desired operating temperatures by providing sufficient viscosity to provide lubrication, while at the same time having sufficient lubrication to minimize friction. Additionally, oils preferably have good thermal conductivity to ensure they efficiently carry away heat generated by the operation of the motor. Finally, it is preferable that the oil have a high electrical resistance.
In certain oil recovery applications, such as for example, steam assisted gravity drainage (SAGD) or the production of heavy oil, increased pumping temperatures result in increased operating temperatures inside the motor. Generally, it is believed that the increase in temperature inside the motor is partially the result of the heat transfer characteristics of the oil. Thus, a temperature rise within the motor will typically be lower if the oil within the motor has a higher heat transfer capacity. It is believed that for every 10° C. increase in the operating temperature of a motor, the reliability and lifetime of the motor can be reduced by approximately 50%. Thus, there is a need for oils having increased heat transfer, lubricity and electrical resistance.